Stand-alone interbody fixation system

ABSTRACT

A stand-alone interbody fixation system having a cage, anterior fixation blade and posterior fixation blade. The cage includes an annular side wall with an open interior and upper and lower surfaces, the cage being configured to fit between end plates of adjacent vertebrae. The anterior fixation blade includes an anterior alignment boss with two opposing outward extending anterior blades with end plate penetrating tips configured to fit within the open interior of the cage. The posterior fixation blade includes a posterior alignment boss with two opposing outward extending posterior blades with end plate penetrating tips configured to fit within the open interior of the cage. The anterior alignment boss and posterior alignment boss being rotatably coupled to each other and with a first opening and a second opening in the annular side wall opposite the first opening. The anterior and posterior fixation blades are counter-rotating blades and the anterior alignment boss and posterior alignment boss are configured to receive or engage a blade activation tool having an anterior engagement portion and a posterior engagement portion configured to rotate the anterior and posterior fixation blades from a stowed position to a deployed condition.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application claims priority from U.S. ProvisionalApplication No. 61/231,967, which was filed on Aug. 6, 2009, and isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to the field of spinalorthopedics, and more particularly to methods and systems for securinginterbody cages within the intervertebral space.

2. Background

The spine is a flexible column formed of a plurality of bones calledvertebra. The vertebrae are hollow and piled one upon the other, forminga strong hollow column for support of the cranium and trunk. The hollowcore of the spine houses and protects the nerves of the spinal cord. Thedifferent vertebrae are connected to one another by means of articularprocesses and intervertebral, fibrocartilaginous bodies.

The intervertebral fibro-cartilages are also known as intervertebraldisks and are made of a fibrous ring filled with pulpy material. Thedisks function as spinal shock absorbers and also cooperate withsynovial joints to facilitate movement and maintain flexibility of thespine. When one or more disks degenerate through accident or disease,nerves passing near the affected area may be compressed and areconsequently irritated. The result may be chronic and/or debilitatingback pain. Various methods and apparatus have been designed to relievesuch back pain, including spinal fusion using a interbody spacer orsuitable graft using techniques such as Anterior Lumbar Interbody Fusion(ALIF), Posterior Lumbar Interbody Fusion (PLIF), or TransforaminalLumbar Interbody Fusion (TLIF) surgical techniques. The implants usedin-these techniques, also commonly referred to as vertebral bodyreplacements (VBR) devices, are placed in the interdiscal space betweenadjacent vertebrae of the spine. Many times an exterior plate is used inconjunction with the VBR to hold the adjacent vertebrae while the fusionoccurs.

Ideally, the interbody spacer should stabilize the intervertebral spaceand allow fusion of the adjacent vertebrae. Moreover, during the time ittakes for fusion to occur, the interbody spacer should have sufficientstructural integrity to withstand the stress of maintaining the spacewithout substantially degrading or deforming and have sufficientstability to remain securely in place prior to actual bone ingrowthfusion.

One significant challenge to providing fusion stability (prior to actualbone ingrowth fusion) is preventing spinal extension during patientmovement. Distraction of the vertebral space containing the fusion graftmay cause the interbody spacer to shift or move disrupting bone ingrowthfusion and causing pain. An exterior plate is often used with theinterbody spacer to hold the adjacent vertebrae while the fusion occurs.

There remains a need for an interbody spacer capable of holding theadjacent vertebrae steady during fusion without the use of externalplates.

SUMMARY OF THE INVENTION

Generally, embodiments of the present invention provide a stand-alonesingle fixation system having a cage, an anterior fixation blade and aposterior fixation blade. The anterior and posterior blades may bepositioned within the cage in a delivery position and rotated from thecage to a deployed position. The stand-alone interbody fixation systemis a pre-assembled multi-component design which integrates a fixationfeature with an interbody spacer, no additional support is required. Thesystem may be used in spinal fusion surgeries including ALIF, PLIF andTLIF procedures, wherein two or more vertebrae are joined or fusedtogether for the treatment of spinal disorders such asspondylolisthesis, scoliosis, severe disc degeneration, or spinalfractures. The system may also be used in open and minimally invasivesurgery (MIS) procedures, and using low profile instrumentationfacilitates a less invasive approach through a smaller incision.

In a first aspect, embodiments of the present invention provide astand-alone interbody fixation system having a cage, anterior fixationblade and posterior fixation blade. The cage includes an annular sidewall with an open interior and upper and lower surfaces, the cage beingconfigured to fit between end plates of adjacent vertebrae. The anteriorfixation blade includes an anterior alignment boss with two opposingoutward extending anterior blades with end plate penetrating tipsconfigured to fit within the open interior of the cage, the anterioralignment boss having first and second ends, the first end of theanterior alignment boss being rotatably coupled with a first opening inthe annular side wall. The posterior fixation blade includes a posterioralignment boss with two opposing outward extending posterior blades withend plate penetrating tips configured to fit within the open interior ofthe cage, the posterior alignment boss having first and second ends, thefirst end being rotatably coupled to the second end of the anterioralignment boss and the second end of the posterior alignment boss beingrotatably coupled with a second opening in the annular side wallopposite the first opening. The anterior and posterior fixation bladesare counter-rotating blades and the anterior alignment boss andposterior alignment boss are configured to receive or engage a bladeactivation tool having an anterior engagement portion and a posteriorengagement portion configured to rotate the anterior and posteriorfixation blades from a stowed position to a deployed condition.

In many embodiments, the cage further includes a blade stop to preventthe blades from exceeding maximum deployment.

In many embodiments, the anterior and posterior blades further include acutting edge between the boss and tip.

In many embodiments, the anterior and posterior blades are curvedblades. The curved blades may be shaped to follow the annular side wallwithin the open interior.

In many embodiments, the anterior and posterior blades may beconstructed of titanium, a titanium alloy, polyetherketoneketone (PEEK),or any other biologically acceptable materials, or a combination of thematerials, capable of penetrating the end plate.

In many embodiments, the anterior engagement portion of the bladeactivation tool is configured to engage the first end of the anterioralignment boss and the posterior engagement portion is configured toengage the first end of the posterior alignment boss through an openingin the anterior alignment boss

In many embodiments, when coupled, the anterior and posterior fixationblades are movable from a fixation blade insertion position forpositioning the coupled anterior and posterior blades in the cage to afixation blade retention position in which the coupled anterior andposterior fixation blades are moved apart and the first end of theanterior alignment boss is within the first opening in the annular sidewall and the second end of the posterior alignment boss is within thesecond opening in the annular side wall. A C-clip may be used to keepthe anterior and posterior fixation blades in the fixation bladeretention position in the cage

In many embodiments, the first and second openings in the annular sidewall include grooves and the first end of the anterior boss and thesecond end of the posterior boss include bumps, the bumps configured tointeract with the grooves and hold the anterior and posterior fixationblades in one or more positions.

In many embodiments, the upper and lower surface include outwardlyprojecting sharp raised ridges, teeth and/or striations.

In another aspect, embodiments of the present invention provide astand-alone interbody fixation system having a cage with an annular sidewall with an open interior and upper and lower surfaces having outwardlyprojecting sharp raised ridges, teeth and/or striations, the cage beingconfigured to fit between end plates of adjacent vertebrae, an anteriorfixation blade having an anterior alignment boss with two curvedopposing outward extending anterior blades shaped to follow the annularside wall within the open interior, the blades being capable ofpenetrating the end plate, the anterior alignment boss being rotatablycoupled to a first opening in the annular side wall, and a posteriorfixation blade having a posterior alignment boss with two curvedopposing outward extending posterior blades shaped to follow the annularside wall within the open interior, the blades being capable ofpenetrating the end plate, the posterior alignment boss being rotatablycoupled to the anterior alignment boss and further rotatably coupledwith a second opening in the annular side wall opposite the firstopening. The anterior and posterior fixation blades are counter-rotatingblades and are configured to receive or engage a counter-rotating bladeactivation tool configured to counter-rotate the anterior and posteriorfixation blades from a stowed position to a deployed condition.

In many embodiments, the anterior and posterior blades further includeend plate penetrating tips.

In many embodiments, the blade activation tool includes an anteriorengagement portion configured to engage the anterior alignment boss anda posterior engagement portion configured to engage the posterioralignment boss.

In many embodiments, the first and second openings in the annular sidewall include grooves and the anterior alignment boss and the posterioralignment boss include bumps, the bumps configured to interact with thegrooves and hold the anterior and posterior fixation blades in one ormore positions.

In many embodiments, the anterior and posterior blades may beconstructed of titanium, a titanium alloy, polyetherketoneketone (PEEK),or any other biologically acceptable materials, or a combination of thematerials, capable of penetrating the end plates. In another aspect,embodiments of the present invention provide a kit for a stand-aloneinterbody fixation system comprising a stand-alone interbody fixationsystem and a counter-rotating blade activation tool. The stand-aloneinterbody fixation system is configured to fit between end plates ofadjacent vertebrae and attach to the end plates. The system comprising acage having an annular side wall with open interior and upper and lowersurfaces, an anterior fixation blade having an anterior alignment bosswith two curved opposing outward extending anterior blades shaped tofollow the annular side wall within the open interior, the blades beingcapable of penetrating the end plate, the anterior alignment boss beingrotatably coupled to a first opening in the annular side wall, and aposterior fixation blade having a posterior alignment boss with twocurved opposing outward extending posterior blades shaped to follow theannular side wall within the open interior, the blades being capable ofpenetrating the end plate, the posterior alignment boss being rotatablycoupled to the anterior alignment boss and further rotatably coupledwith a second opening in the annular side wall opposite the firstopening. The counter-rotating blade activation tool being configured tocounter-rotate the anterior and posterior fixation blades from a stowedposition to a deployed condition.

In many embodiments, the kit further includes a bone graft or biologicmaterial sized to fit within the interior of the cage when the anteriorand posterior fixation blades are in the stowed position.

In many embodiments, the first and second openings in the annular sidewall include grooves and the anterior alignment boss and the posterioralignment boss include bumps, the bumps configured to interact with thegrooves and hold the anterior and posterior fixation blades in one ormore positions.

In many embodiments, the anterior engagement portion of the bladeactivation tool is configured to engage a first end of the anterioralignment boss and the posterior engagement portion is configured toengage a first end of the posterior alignment boss through an opening inthe anterior alignment boss.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described with reference to the accompanyingdrawings.

FIGS. 1-10K show various views of one embodiment of a stand-aloneinterbody fixation system.

FIG. 11 shows another assembly embodiment of a stand-alone interbodyfixation system.

FIGS. 12A-16C show other embodiments of stand-alone interbody fixationsystems.

FIG. 17 shows other embodiments of anterior and/or posterior blades.

FIGS. 18A-20 show embodiments of deployment instrument for use withstand-alone interbody fixation systems.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention will now be described with reference to theFigures, wherein like numerals reflect like elements throughout. Theterminology used in the description presented herein is not intended tobe interpreted in any limited or restrictive way, simply because it isbeing utilized in conjunction with detailed description of certainspecific embodiments of the invention. Furthermore, embodiments of theinvention may include several novel features, no single one of which issolely responsible for its desirable attributes or which is essential topracticing the invention described herein.

FIGS. 1 and 2 illustrate schematically one embodiment of a stand-aloneinterbody fixation system 100. The stand-alone interbody fixation system100 is a pre-assembled multi-component design which integrates afixation feature with an interbody spacer with no additional supportrequired. In preferred embodiments, the system 100 is used in spinalfusion surgeries including, but not limited to Anterior Lumbar InterbodyFusion (ALIF), Posterior Lumbar Interbody Fusion (PLIF), orTransforaminal Lumbar Interbody Fusion (TLIF), lateral and cervicalprocedures, wherein two or more vertebrae are joined or fused togetherfor the treatment of spinal disorders such as spondylolisthesis,scoliosis, severe disc degeneration, or spinal fractures. While theembodiments are described primarily in the context of an ALIF procedure,use with other procedures are also contemplated. The system 100 may beused in a variety of spinal procedures, including open procedures andminimally invasive surgery (MIS) procedures using low profileinstrumentation which facilitates a less invasive approach through asmaller incision. As can be understood by one skilled in the art, theseembodiments are shown for illustrative purposes and are not intended tolimit the scope of the invention.

The unique design of the stand-alone interbody fixation system 100provides a solid fixation in all aspects (flexion, extension, torsion,rotation, migration). In many embodiments, the system 100 is configuredto use a single instrument to distract, insert and deploy the system.The design allows for multiple footprint shapes, ranging from 20-40 mmin both length and width to ensure adequate contact with cortical rim.In many embodiments, the design includes a tapered leading portion thatallows smooth insertion and deployment. The height may range from 8-20mm, but other heights are also contemplated, depending on location.Lordosis ranging from 0-20 degrees to accommodate surgical needs.

The system 100 disclosed uses counter rotating blades 110, 115 thatprovide 4 points of fixation with 2-10 mm of blade engagement. In orderto maintain bone purchase or blade engagement for each implant heightand footprint, the blade length may be increased or decreased toaccommodate the cage height. As the blade rotates from its restingposition to the deployed position, the amount of exposed blade iscontrolled across the various implant sizes. While counter rotatingblades are disclosed, other embodiments may deploy the blades rotatingin the same direction. Secure deployment and engagement of blades withpositive feedback when blades deployed and locked. Internal lockprevents accidental deployment and positive tangible feedback to surgeonwhen the blades are fully deployed. The blades are securely held inplace and some embodiments may include elements to preventover-deployment. In some embodiments, the ability to reverse deploymentand remove or reposition implant may be desirable. The unique bladeshape allows adequate space to pack bone graft before insertion. Thereare also access ports in the interbody spacer or cage to allowadditional bone graft to be added after insertion/deployment. Someembodiments of the blade shape geometry may also pull the endplatestogether when deployed.

The stand-alone interbody fixation system 100 includes a cage 105, ananterior fixation blade 110 and a posterior fixation blade 115. FIG. 1is a perspective view showing the anterior 110 and posterior 115 bladeswithin the cage 105 in a delivery position and FIG. 2 is a perspectiveview showing the anterior 110 and posterior 115 blades in the deployedposition. FIG. 3 is a top view showing an embodiment in which the curvedanterior 110 and posterior 115 blades are designed to follow shape ofthe interior of the cage 105 resulting in axial windows 130 that may beused for packing of bone graft material within to expedite the fusion ofthe cage in the spinal column. FIG. 4 is a view looking posteriorlyshowing the cage 105 and the anterior 110 and posterior 115 blades inthe deployed position. FIG. 5A is a side view and FIG. 5B is a frontview of the cage 105 and the anterior 110 and posterior 115 blades inthe stowed position.

In an ALIF procedure, the stand-alone interbody fixation system 100 isinserted and fixated from an anterior approach so that posteriormuscular structures are preserved and surgical morbidity associated with360° is eliminated. Once inserted, the anterior fixation blade 110rotates in a clockwise rotation 120 and the posterior fixation blade 115rotates in a counterclockwise rotation 125, shown in FIG. 2, biting intothe vertebral end plates (not shown). While embodiments below aredescribed primarily in the context of two counter rotating blades, othernumber of blades and rotations are also contemplated.

FIGS. 6A-6C show some of the assembly features of the stand-aloneinterbody fixation system 100. FIG. 6A is a top view showing theanterior 110 and posterior 115 blades positioned for insertion with theaxial window 130 between for placement of bone graft or other types ofbone growth materials or biologics (not shown). FIG. 6B is a side viewshowing that when the anterior 110 and posterior 115 blades in thestowed or rest position they are under the boundaries or surfaces of thecage 105 geometry. This allows the system 100 to be inserted between theend plates of adjacent vertebrae without anterior 110 and posterior 115blades contacting the end plates. FIG. 6C is a perspective view of thesystem showing a stop 240 on the cage 105 that the anterior 110 andposterior 115 blades may contact during deployment to prevent the bladesfrom exceeding maximum deployment.

FIGS. 7A-7C show one embodiment of an anterior fixation blade 110 thatincludes curved blades designed to penetrate the end plates of adjacentvertebrae. The curved blades may have a smooth curve or may be a seriesof straight sections. Using curved blades maximizes graft volume andminimizes graft displacement during deployment. The anterior fixationblade 110 may be constructed of titanium, a titanium alloy,polyetherketoneketone (PEEK), or any other biologically acceptablematerials that would engage the spine plate and provide a rigidstructure. The anterior fixation blade 110 may be constructed using onematerial or a combination of the materials. The anterior fixation blade110 includes blade tips 135 that are designed to penetrate bone with asharp tip feature and continue to a leading edge or cutting edge 140,similar to a sickle. The blade tips 135 positioned at the outerperimeter of an anterior fixation blade 110 diameter facilitateimmediate bone engagement at initial deployment. The blades are attachedto an axial alignment boss 145. The blades include cutting edge thatspans the entire length of the blade from the boss to the tip for allsizes. The axial alignment boss 145 has a first end 150 and a second end155. The first end 150 includes a cylindrical rotating alignment featurethat includes one or more blade resistance/securing/locking feature 160that couples to the cage 105 (discussed below). The first end 150further includes a drive mechanism 152 or recess configured to engage adeployment instrument for rotating the anterior fixation blade 110between a closed and open position. The drive mechanism may be a Hex,Hex-a-lobe, spline, double hex, Bristol, polydrive, torq-set, square,slotted, Phillips, etc. The second end 155 of the boss 145 includes anopening 165 configured to interact with the posterior fixation blade 115and also allows insertion of the deployment instrument for actuation ofthe posterior fixation blade 115.

FIGS. 8A-8E show one embodiment of a posterior fixation blade 115 thatincludes curved blades designed to penetrate the end plates of adjacentvertebrae. Smooth curved or a series of straight sections that form thecurved blades maximize graft volume and minimize graft displacementduring deployment. The posterior fixation blade 115 may be constructedof titanium, a titanium alloy, polyetherketoneketone (PEEK), or anyother biologically acceptable inert materials that would provide a rigidstructure. The posterior fixation blade 115 may also be constructed witha combination of the materials. The posterior fixation blade 115includes blade tips 170 that are designed to penetrate with a sharp tipfeature and continue to a sharp leading edge or cutting edge 175,similar to a sickle. The blade tips 170 at the outer perimeter of thediameter facilitate immediate bone engagement at initial deployment. Theblades are attached to an axial alignment boss 180. The blades includecutting edge that spans the entire length of the blade from the boss tothe tip for all sizes. The axial alignment boss 180 has a first end 185and a second end 190. The first end 185 is designed to slidably fitwithin the opening 165 of the anterior fixation blade 110. The first end185 further includes a drive mechanism 187 or recess for rotating theblade between a closed and open position. The drive mechanism may be aHex, Hex-a-lobe, spline, double hex, Bristol, polydrive, torq-set,square, slotted, Phillips, etc. The second end 190 includes acylindrical rotating alignment feature that includes one or more bladeresistance/securing/locking feature 195 configured to couple with thecage 105.

FIGS. 9A-9F show different views and features of the cage 105. The cage105 may be made of a rigid construction and preferably provided inseveral different sizes and shapes to fill differently sized evacuatedspaces in differently sized individuals. The cage 105 has an interioropening 200 for storage of the blades 110, 115. The curves shape of theblades 110, 115 allow packing of bone graft material (see FIG. 3). Thecage 105 may be constructed of a radiolucent material, such aspolyetherketoneketone (PEEK), a commercially pure titanium, a titaniumalloy or any other biologically acceptable inert materials that wouldprovide the cage with a rigid structure.

The cage 105 is annular in configuration having an upper surface 205 andan opposed lower surface 210 configured to engage superiorly andinferiorly the end plates of adjacent vertebrae, and an annular sidewall 215 around the hollow interior opening 200. The annular side wall215 may have varying height, length, and thickness, and may includelordotic angle for better anatomical fit. In some embodiments, aplurality of outwardly projecting sharp raised ridges/teeth/striations220 are formed on the surfaces 205, 210 for biting into and gripping thevertebral end plates (not shown). The ridges 220 may have a variablethickness, height, and width as well as an angle with respect tosurfaces. The ridges 220 may be disposed at slightly offset angles withrespect to each other or, alternatively with respect to the ridges ondifferent portions of the cage, to reduce the possibility of the ridgessliding in any direction along the end plates and to prevent rotation ofthe cage on the end plate. For example, the figures show the ridges 220on one side or portion of the surface 205 are all in parallel alignment,but misaligned with the ridges on the other side or portion. While itmay be preferable that the ridges 220 are identical in configuration onthe upper and lower surfaces, in some embodiments, the ridges or teethdifferent or have a different pattern for each surface.

A plurality of openings 225, 230 are disposed in the side wall 215 ofthe cage 105. Opening 225 a is configured to receive or engage end 150of fixation blade 110 and opening 225 b is configured to receive orengage end 190 of fixation blade 115. Other openings 230 spaced aboutthe cage may be configured to receive or engage an insertion tool orblade activation tool (not shown), or used to pack bone or othersuitable bone graft material. Openings 225 a, 225 b are generallycircular in shape and include blade resistance/locking features 235 a,235 b to hold blades in one or more positions. These features 235 a, 235b may include grooves, notches or dimples that couple or interact withridges, tabs or bumps 160, 195 on blades 110, 115. When end 150 offixation blade 110 is inserted into opening 225 a, bumps 160 interactwith one of the grooves 235 a. As the blade is rotated, the bumps 160may move from one set of grooves 235 a in a stored position to anotherset of grooves 235 a in the deployed position, to form a lockingmechanism. When end 190 of fixation blade 115 is inserted into opening225 b, bumps 195 interact with one of the grooves 235 b. As the blade isrotated, the bumps 195 may move from one set of grooves 235 b in astored position to another set of grooves 235 a in the deployedposition, to form a locking mechanism. Openings 230 may be generallyrectangular in shape to accommodate an insertion tool or bladeactivation tool having a center blade activation portion disposedbetween a pair of prongs, so that the tool can grip the openings 230 ofthe cage and/or rotate the blades. A blade stopping feature 240 may alsobe used to contact the blades and prevent the blades from rotating morethen desired angle.

FIGS. 10A-10H show one example of an assembly method for system 100. Theanterior fixation blade 110 and posterior fixation blade 115 are aligned(FIG. 10A) and the first end 185 of the posterior fixation blade 115 isinserted into the opening 160 near the second end 155 of the anteriorfixation blade 110. When fully inserted, the distance between the firstend 150 of the anterior fixation blade 110 and the second end 190 of theposterior fixation blade 115 is less than an interior distance betweenthe first opening 225 a and second opening 225 b of the cage 105 (FIG.10B). With the blades 110, 115 combined in this manner, they may beinserted into the central opening 200 and positioned within the cage 105(FIGS. 10C, 10D). The blades 110, 115 may then be moved or extended inopposite directions until the first end 150 of the anterior fixationblade 110 is inserted into the first opening 225 a and the second end190 of the posterior fixation blade 115 is inserted into the secondopening 225 b and the blades are rotated to the stored position (FIGS.10E-10I). To keep the blades 110, 115 in the extended position, a C-clip245 is slid over the boss 180 of the posterior fixation blade 115 (FIG.10J) to keep the ends of the anterior and posterior fixation blades 110,115 within the openings 225 a, 225 b forming the system 100 (FIG. 10K).

FIG. 11 is an exploded view showing another embodiment of a stand-aloneinterbody fixation system 300, having a cage 305, an anterior fixationblade 310 and a posterior fixation blade 315. The cage 305 may besimilar to cage 105 and may include one or more of the featuresdisclosed above for cage 105. The anterior and posterior fixation blades310, 315 may include one or more of the features disclosed above forblades 110, 115. In the embodiment shown, the anterior and posteriorfixation blades 310, 315 are straight. The cage 305 includes a firstopening 325 a with an open top portion configured to couple with a firstend 350 of the anterior fixation blade 310 and a second opening 325 bconfigured to couple with a second end 390 of the posterior blade 315.To assemble the system 300, a first end 380 of the posterior fixationblade 315 is coupled with a second end 355 of the anterior fixationblade 310. The joined fixation blades 310, 315 are then advanced towardthe cage 305 and the second end 390 of the posterior fixation blade 315is inserted into the second opening 325 b. The first end 350 of theanterior fixation blade 310 is inserted into the open top portion of thefirst opening 325 a, snapping in place. The first opening 325 a may havespring like side portions that hold the first end 350 of the anteriorfixation blade 310 in place. The ends 350, 390 of the blades may alsoinclude ridges, tabs or bumps that engage or couple with grooves,notches or dimples in openings 325 a and 325 b, similar to thosedisclosed above for system 100.

FIGS. 12A-16C show different embodiments of stand-alone interbodyfixation systems which integrates a fixation feature with an interbodyspacer with no additional support required. One or more of the elementsand feature disclosed above for the stand-alone interbody fixationsystem 100 and 300 may be incorporated into the systems below.

FIGS. 12A and 12B show one embodiment of a stand-alone single anteriorblade interbody fixation system 400 having one fixation blade 410, withmultiple axial graft windows 430 and transverse inner walls. In thisembodiment, the fixation blade 410 is a true s-shaped blade positionedtoward a front portion of the implant and may used for anterior fixation(a reversed design with the blade toward the back portion may be forposterior fixation) and the transverse inner walls create a robust cagewith center struts and allow axial graft windows.

FIGS. 13A and 13B show another embodiment of a stand-alone double bladeinterbody fixation system 500 having two fixation blades 510, 515,central graft window 530 and transverse inner walls. This embodimentincludes fixation blades that are true s-shaped blades positioned onopposite sides of the central graft window 530 for anterior andposterior fixation, and the transverse inner walls create a robust cagewith center struts and allow a larger axial graft window.

FIGS. 14A and 14B show another embodiment of a stand-alone singleanterior blade interbody fixation system 600 having a single blade 610with multiple cutting edges, posterior graft window and transverse innerwall. The multiple cutting edges of the fixation blade are true s-shapedwith sharp tips used for anterior to posterior fixation, includingmidline fixation. The transverse inner wall create a robust cage andallows posterior graft window.

FIGS. 15A-15C show another embodiment of a stand-alone interbodyfixation system 700 having two fixation blades 710, 715, with multiplecutting edges and graft window. This embodiment includes fixation bladesthat are true s-shaped blades for fixation, and superior anterior andposterior fixation.

FIGS. 16A-16C show another embodiment of a stand-alone interbodyfixation system 800 two fixation blades 810, 815 with multiple cuttingedges and graft window. This embodiment includes fixation blades withthe maximum achievable blade length and simple blade to cage assembly.

FIGS. 17A-17D are views showing other embodiments of anterior and/orposterior blades suitable for use in the embodiments disclosed above.The blades may be curved blades having a smooth curve or may be a seriesof straight sections or both. The blades may also vary in thickness inboth height and width.

Instrument Concepts/Features

In some embodiments the deployment instrument will have two concentriccounter rotating shafts. The counter-rotation can be achieved with aseries gears (shown in FIGS. 18A-18C) or with two levers (shown in FIGS.19A-19B). The tip of the instrument may have an interference fit tofixate to the implant. The implant holder will be cannulated to allowthe blade deployment instrument to pass through. The implantinserter/distractor will also be cannulated to allow the deploymentshafts to pass through.

FIGS. 20A-20C show another embodiment of a deployment instrumentinteracting with the cage 105. Handles are used to deploy the blades(not shown).

Example embodiments of the methods and components of the presentinvention have been described herein. As noted elsewhere, these exampleembodiments have been described for illustrative purposes only, and arenot limiting. Other embodiments are possible and are covered by theinvention. Such embodiments will be apparent to persons skilled in therelevant art(s) based on the teachings contained herein. Thus, thebreadth and scope of the present invention should not be limited by anyof the above-described exemplary embodiments, but should be defined onlyin accordance with the following claims and their equivalents.

1-20. (canceled)
 21. An intervertebral fixation device for fusionsurgery for insertion between a first vertebra and an adjacent secondvertebra, comprising: an annular wall forming a cage configured forinsertion between the first vertebra and the second vertebra, theannular wall including a first surface that engages a first endplate ofthe first vertebra and a second surface that engages a second endplateof the second vertebra; a first blade rotatably coupled within ananterior portion of the cage and including a curved portion shaped tofollow an anterior portion of an interior surface of the side wall; anda second blade rotatably coupled within a posterior portion of the cageand including a curved portion shaped to follow a posterior portion ofan interior surface of the side wall, wherein the first and secondblades stow remain within the cage in a first configuration andpartially extend outside the first and second surfaces of the annularwall in a second configuration.
 22. The device of claim 21, wherein thefirst and second blades include counter-rotating blades.
 23. The deviceof claim 21, wherein at least one of the first and second bladesincludes a straight section.
 24. The device of claim 21, wherein theanterior portion of the annular side wall includes a first heightgreater than a second height of the posterior portion of the annularside wall.
 25. The device of claim 21, wherein the first and secondblades rotate about a common axis extending through the center of theanterior portion and posterior portion of the annular side wall.
 26. Thedevice of claim 21, further comprising a first boss extending anteriorlyfrom the first blade for rotational engagement with a first opening inthe anterior portion of the side wall.
 27. The device of claim 21,further comprising a second boss extending posteriorly from the secondblade for rotational engagement with a second opening in the posteriorportion of the side wall.
 28. The device of claim 21, wherein the firstblade includes a posterior alignment opening for receiving an anterioralignment boss of the second blade.
 29. The device of claim 21, whereinthe second blade includes an anterior alignment opening for receiving aposterior alignment boss of the first blade.
 30. The device of claim 21,further comprising a clip between the first and second blades configuredto keep the first and second blades within the cage in the firstconfiguration.